Yarn tension control device

ABSTRACT

A yarn tension control device controls tension in a running yarn. The tension control device includes a housing having a yarn guiding inlet for receiving running yarn at an unwinding tension from a yarn supply source, and a yarn guiding outlet for guiding running yarn exiting the housing at a delivery tension. First and second opposing yarn engaging surfaces are disposed between the inlet and the outlet, and are adapted to frictionally engage opposite sides of the running yarn along a path of yarn travel through the housing. The first and second yarn engaging surfaces define a respective plurality of sequentially spaced friction rolls. A biasing assembly resiliently urges the first and second yarn engaging surfaces together. The opposing friction rolls cooperate to form a number of sequentially spaced nip points adapted to adjust yarn delivery tension in response to stress variations in running yarn entering the housing.

TECHNICAL FIELD AND BACKGROUND

The present disclosure relates broadly to the textile industry, and morespecifically, to a yarn tension control device which compensates forstress variations in running yarn. One cause of stress variation relatesdirectly to the shrinking size of the yarn supply package as yarn isunwound and pulled downstream to a textile machine. In one exemplaryimplementation, the present invention adjusts unwinding tension in therunning yarn in order to achieve a more uniform and constant deliverytension to the textile machine.

SUMMARY OF EXEMPLARY EMBODIMENTS

Various exemplary embodiments of the present invention are describedbelow. Use of the term “exemplary” means illustrative or by way ofexample only, and any reference herein to “the invention” is notintended to restrict or limit the invention to exact features or stepsof any one or more of the exemplary embodiments disclosed in the presentspecification. References to “exemplary embodiment,” “one embodiment,”“an embodiment,” “various embodiments,” and the like, may indicate thatthe embodiment(s) of the invention so described may include a particularfeature, structure, or characteristic, but not every embodimentnecessarily includes the particular feature, structure, orcharacteristic. Further, repeated use of the phrase “in one embodiment,”or “in an exemplary embodiment,” do not necessarily refer to the sameembodiment, although they may.

One object of the exemplary embodiments described herein is to providean improved tension control device which delicately senses stressvariations in a running yarn, which reacts to such variations so as toaugment or to reduce friction resistance on the yarn for establishing adesired uniform tension therein, especially in response to variations ofunwinding tension of the supply yarn source.

According to one exemplary embodiment, the invention may comprise a yarntension control device for controlling tension in a running yarn. Thetension control device includes a housing having a yarn guiding inletfor receiving running yarn at an unwinding tension from a yarn supplysource, and a yarn guiding outlet for guiding running yarn exiting thehousing at a delivery tension. First and second opposing yarn engagingsurfaces are disposed between the inlet and the outlet, and are adaptedto frictionally engage opposite sides of the running yarn along a pathof yarn travel through the housing. The first and second yarn engagingsurfaces define a respective plurality of sequentially spaced frictionrolls. Means are provided for resiliently urging the first and secondyarn engaging surfaces together. The opposing friction rolls cooperateto form a plurality of sequentially spaced nip points adapted to adjustyarn delivery tension in response to stress variations in running yarnentering the housing. As such, greater frictional resistance is appliedat the nip points to running yarn entering the housing at a relativelylow degree of unwinding tension, and lesser frictional resistance isapplied at the nip points to running yarn entering the housing at arelatively high degree of unwinding tension.

Use of the terms “upstream” and “downstream” refer herein to relativelocations (or movement) of elements or structure to other elements orstructure along or adjacent the path of yarn travel. In other words, afirst element or structure which is encountered along or adjacent thepath of yarn travel before a second element or structure is consideredto be “upstream” of the second element or structure, and the secondelement structure is considered to be “downstream” of the first.

The term “sequentially spaced” is defined herein to mean the physicaland/or temporal spacing of elements or structure downstream along oradjacent the path of yarn travel.

The term “housing” refers broadly herein to any open, closed, orpartially open or partially closed structure.

According to another exemplary embodiment, a pivoted rocker block iscarried by the housing, and the first yarn engaging surface is definedby an inside surface of the rocker block.

According to another exemplary embodiment, the second yarn engagingsurface is defined by a fixed inside wall of the housing adjacent thefirst yarn engaging surface defined by the rocker block.

According to another exemplary embodiment, the yarn guiding inlet of thehousing is longitudinally offset from the sequentially spaced nip pointsalong the path of yarn travel.

The term “longitudinally offset” is defined herein to mean located alaterally spaced distance outside a longitudinal path of otherwisestraight travel between two spaced points.

According to another exemplary embodiment, the rocker block is mountedat a pivot point located upstream of the nip points and adjacent asecond inside wall of the housing opposite the second yarn engagingsurface.

According to another exemplary embodiment, the rocker block defines asecond inside surface extending at an angle downstream from the pivotpoint to the first yarn engaging surface, and wherein the rocker blockhas a center of gravity spaced downstream from the pivot point.

According to another exemplary embodiment, the yarn guiding outlet ofthe housing is longitudinally offset from the sequentially spaced nippoints along the path of yarn travel.

According to another exemplary embodiment, the friction rolls of thefirst and second yarn engaging surfaces are in substantial registrationon opposite sides of the running yarn when the surfaces are resilientlyurged together. Upon slight pivoting movement of the rocker block, thefriction rolls of the second yarn engaging surface shift (outwardly andlongitudinally) along the path of yarn travel relative to the frictionrolls of the first yarn engaging surface, thereby reducing frictionalresistance applied to the running yarn.

According to another exemplary embodiment, the means for resilientlyurging the first and second yarn engaging surfaces together includes acompression spring.

According to another exemplary embodiment, the compression spring isaxially oriented to create a biasing force acting adjacent thesequentially spaced nip points defined by the first and second yarnengaging surfaces.

According to another exemplary embodiment, means are provided forselectively adjusting the biasing force created by the compressionspring.

According to another exemplary embodiment, the means for selectivelyadjusting the biasing force includes a rotatable cam wheel andspring-engaging ball.

According to another exemplary embodiment, the cam wheel defines anumber of circumferentially spaced recessed cam surfaces of varyingdepth.

According to another exemplary embodiment, a yarn cleaner is locatedupstream of the housing.

BRIEF DESCRIPTION OF THE DRAWINGS

The description of exemplary embodiments proceeds in conjunction withthe following drawings, in which:

FIG. 1 is an environmental perspective view of a yarn tension controldevice according to one exemplary embodiment of the present invention;

FIG. 2 is a further perspective view of the yarn tension control device;

FIG. 3 is an exploded view of the yarn tension control device;

FIG. 4 is a cross-sectional view of the yarn tension control device withthe cam wheel indexed at a position of minimum frictional resistance;and

FIG. 5 is a further cross-sectional view of the yarn tension controldevice with the cam wheel indexed at a position of maximum frictionalresistance.

DESCRIPTION OF EXEMPLARY EMBODIMENTS AND BEST MODE

The present invention is described more fully hereinafterwith referenceto the accompanying drawings, in which one or more exemplary embodimentsof the invention are shown. Like numbers used herein refer to likeelements throughout. This invention may, however, be embodied in manydifferent forms and should not be construed as limited to theembodiments set forth herein; rather, these embodiments are provided sothat this disclosure will be operative, enabling, and complete.Accordingly, the particular arrangements disclosed are meant to beillustrative only and not limiting as to the scope of the invention,which is to be given the full breadth of the appended claims and any andall equivalents thereof. Moreover, many embodiments, such asadaptations, variations, modifications, and equivalent arrangements,will be implicitly disclosed by the embodiments described herein andfall within the scope of the present invention.

Although specific terms are employed herein, they are used in a genericand descriptive sense only and not for purposes of limitation. Unlessotherwise expressly defined herein, such terms are intended to be giventheir broad ordinary and customary meaning not inconsistent with thatapplicable in the relevant industry and without restriction to anyspecific embodiment hereinafter described. As used herein, the article“a” is intended to include one or more items. Where only one item isintended, the term “one”, “single”, or similar language is used. Whenused herein to join a list of items, the term “or” denotes at lease oneof the items, but does not exclude a plurality of items of the list.

For exemplary methods or processes of the invention, the sequence and/orarrangement of steps described herein are illustrative and notrestrictive. Accordingly, it should be understood that, although stepsof various processes or methods may be shown and described as being in asequence or temporal arrangement, the steps of any such processes ormethods are not limited to being carried out in any particular sequenceor arrangement, absent an indication otherwise. Indeed, the steps insuch processes or methods generally may be carried out in variousdifferent sequences and arrangements while still falling within thescope of the present invention.

Additionally, any references to advantages, benefits, unexpectedresults, or operability of the present invention are not intended as anaffirmation that the invention has been previously reduced to practiceor that any testing has been performed. Likewise, unless statedotherwise, use of verbs in the past tense (present perfect or preterite)is not intended to indicate or imply that the invention has beenpreviously reduced to practice or that any testing has been performed.

Referring now specifically to the drawings, a yarn tension controldevice according to one exemplary embodiment of the present invention isillustrated in FIG. 1 and shown generally at reference numeral 10. Theexemplary tension control device 10 is located between an upstream yarnsupply package 11 (e.g., bobbin) and a downstream textile machine, andmay be vertically mounted on a frame member 12 attached to a creel orstructural component of the textile machine. The tension control device10 is applicable for use in combination with any textile machine, suchas a yarn cabler, and other machines that utilize yarn in themanufacture or processing of a textile product.

As running yarn 14 is pulled from the supply package 11 to the textilemachine, the interposed tension control device 10 applies varyingresistance to the yarn 14 by friction engagement that varies in responseto the unwinding (or incoming) tension in running yarn 14 entering thedevice 10, such that the delivery tension of running yarn 14 exiting thedevice 10 is maintained at a relatively uniform and constant level.Thus, the tension control device 10 applies greater frictionalresistance to running yarn 14 that is initially at a low degree ofunwinding tension, and applies lesser frictional resistance to runningyarn 14 of higher unwinding tension. The frictional restraint isresponsive to variations in yarn tension to increase or decrease thetension as a result of the amount of deflection in the yarn.

Referring now to FIGS. 1, 2, and 3, the exemplary yarn tension controldevice 10 comprises a generally open-structure housing 15 having a yarnguiding inlet 16 for receiving running yarn 14 entering the housing 15at an unwinding tension from the yarn supply package 11, and a yarnguiding outlet 17 for guiding the running yarn 14 exiting the housing 15at a delivery tension to the downstream textile machine (not shown). Apivoted rocker block 20 is carried by the housing 15, and locatedbetween the yarn inlet 16 and yarn outlet 17. The rocker block 20 ispivotably mounted at a front end pivot point 21 via threaded pin 22(e.g., shoulder bolt), and has a generally trapezoidal shape withopposite sides 23 and 24 being substantially parallel and sides 25 and26 being non-parallel. A compression spring 27 may reside between theannular shoulder of pin 22 and an annular interior surface (not shown)of the rocker block 20 to resiliently urge and tension the rocker block20 inside the housing 15, and thereby limit its vibration duringoperation of the yarn tension control device 10. Block side 25 of therocker block extends from the front end at an angle (α) of approximately45 degrees (See FIG. 4) to the side 23.

The side 24 (or inside surface) of the rocker block 20 is longitudinallyoffset from the yarn inlet 16 and defines a first yarn engaging surfacecomprising multiple, sequentially-spaced friction rolls 28 and 29. Thefriction rolls 28, 29 may be either separately or integrally formed withthe rocker block 20, and may be rotatable or fixed. In one embodiment,the friction rolls 28, 29 are separately formed and comprise a generallywear-resistant material, such as a ceramic. The first yarn engagingsurface 24 of the rocker block 20 cooperates with a second yarn engagingsurface 31 defined by a fixed inside wall of the housing 15 and abiasing force, described below, to frictionally engage opposite sides ofthe running yarn 14 along its path of travel through the housing 15. Thesecond yarn engaging surface 31 may have identical friction rolls 32 and33 arranged in substantial registration with friction rolls 28, 29 onopposite sides of the running yarn 14, such that respective pairs offriction rolls 28, 32 and 29, 33 cooperate to form sequentially spacedand resiliently biased nip points 34 and 35. The nip points 34, 35 arelongitudinally offset from the yarn inlet 16 and yarn outlet 17 of thehousing 15, and adjust to vary tension in the running yarn 14. In oneimplementation, the nip points 34, 35 cooperate to delicately adjustyarn delivery tension in response to stress variations in running yarn14 entering the housing 15, such that greater frictional resistance isapplied at the nip points 34, 35 to running yarn 14 at a relatively lowdegree of unwinding tension, and lesser frictional resistance is appliedat the nip points 34, 35 to running yarn 14 at a relatively high degreeof unwinding tension. While the present embodiment utilizes twosequentially spaced nip points 34, 35, it is understood that additionalspaced nip points may be added in achieving the desired yarn tensioncontrol.

As best shown in FIGS. 4 and 5, the rocker block 20 is resiliently urgedtowards the inside wall of the housing 15 using a compression spring 41(or other biasing means), thereby urging the first and second yarnengaging surfaces 24, 31 together on opposite sides of the running yarn14. In the embodiment shown, the compression spring 41 is axiallyoriented inside a cylindrical opening 42 formed with the rocker block20, and operates to direct a biasing force along a notional lineextending through an area of the nip points 34, 35. The degree ofbiasing force may be selectively adjusted or indexed using a rotatablecam wheel 44 and spring-engaging ball 45. The cam wheel 44 has a numberof circumferentially-spaced, recessed cam surfaces 46A, 46B, 46C, and46D of varying depth. The cam surfaces 46A-46D are designed to receivethe ball 45, such that deeper surfaces 46A, 46B cause less compressionof the spring 41 and result in less force acting against the rockerblock 20. In this case, the sensitivity of the nip points 34, 35 totension variation increases. FIG. 4 shows the cam wheel 44 indexed at aposition of minimum frictional resistance. Conversely, the more shallowcam surfaces 46C, 46D cause increased compression of the spring 41, andresult in greater force acting against the rocker block 20 and lesssensitive nip points 34, 35. FIG. 5 shows the cam wheel 44 indexed at aposition of maximum frictional resistance. For added convenience, thecam wheel 44 may further comprise a manual turn knob 48 and indexingindicia 49, shown in FIGS. 2 and 3, used to select the desired degree ofspring compression (or biasing force). In this embodiment, the center ofgravity of the rocker block 20 is spaced away (or downstream) of thepivot point 21, and in an area of the nip points 34, 35.

In addition to the above, the tension control device 10 may include aseparately attached yarn cleaner 50 (and “de-tangler”) comprising a yarnreceiving eyelet 51 and support arm 52 attached to the housing 15 usinghardware 53, such as screws. The eyelet 51 is located upstream of thehousing 15 in the path of yarn travel, and frictionally engages therunning yarn 14 to clean and de-tangle the yarn 14 before the yarn 14passes into and through the housing inlet 16.

Exemplary embodiments of the present invention are described above. Noelement, act, or instruction used in this description should beconstrued as important, necessary, critical, or essential to theinvention unless explicitly described as such. Although only a view ofthe exemplary embodiments have been described in detail herein, thoseskilled in the art will readily appreciate that many modifications arepossible in these exemplary embodiments without materially departingfrom the novel teachings and advantages of this invention. Accordingly,all such modifications are intended to be included within the scope ofthis invention as defined in the appended claims.

In the claims, any means-plus-function clauses are intended to cover thestructures described herein as performing the recited function and notonly structural equivalents, but also equivalent structures. Thus,although a nail and a screw may not be structural equivalents in that anail employs a cylindrical surface to secure wooden parts together,whereas a screw employs a helical surface, in the environment offastening wooden parts, a nail and a screw may be equivalent structures.Unless the exact language “means for” (performing a particular functionor step) is recited in the claims, a construction under §112, 6thparagraph is not intended. Additionally, it is not intended that thescope of patent protection afforded the present invention be defined byreading into any claim a limitation found herein that does notexplicitly appear in the claim itself.

1. A yarn tension control device for controlling tension in a runningyarn, said tension control device comprising: a housing having a yarnguiding inlet for receiving running yarn at an unwinding tension from ayarn supply source, and a yarn guiding outlet for guiding the runningyarn exiting said housing at a delivery tension; first and secondopposing yarn engaging surfaces disposed between said inlet and saidoutlet, and adapted to frictionally engage opposite sides of the runningyarn along a path of yarn travel through said housing; said first andsecond yarn engaging surfaces defining a respective plurality ofsequentially spaced friction rolls downstream of said yarn guidinginlet; a pivoted rocker block carried by said housing, and wherein saidfirst yarn engaging surface is defined by an inside surface of saidrocker block, and wherein said rocker block comprises a single pivotpoint, and said pivot point being located upstream of a leading one ofsaid friction rolls; and means for resiliently urging said first andsecond yarn engaging surfaces together, wherein said opposing frictionrolls cooperate to form a plurality of sequentially spaced nip pointsadapted to adjust yarn delivery tension in response to stress variationsin running yarn entering said housing, such that greater frictionalresistance is applied at said nip points to running yarn entering saidhousing at a relatively low degree of unwinding tension, and lesserfrictional resistance is applied at said nip points to running yarnentering said housing at a relatively high degree of unwinding tension.2. A yarn tension control device according to claim 1, wherein saidsecond yarn engaging surface is defined by a fixed inside wall of saidhousing adjacent the first yarn engaging surface defined by said rockerblock.
 3. A yarn tension control device according to claim 2, whereinthe yarn guiding inlet of said housing is longitudinally offset from thesequentially spaced nip points along the path of yarn travel.
 4. A yarntension control device according to claim 3, wherein said rocker blockis mounted adjacent a second inside wall of said housing opposite saidsecond yarn engaging surface.
 5. A yarn tension control device accordingto claim 4, wherein said rocker block defines a second inside surfaceextending at an angle downstream from the pivot point to said first yarnengaging surface, and wherein said rocker block has a center of gravityspaced downstream from the pivot point.
 6. A yarn tension control deviceaccording to claim 5, wherein the yarn guiding outlet of said housing islongitudinally offset from the sequentially spaced nip points along thepath of yarn travel.
 7. A yarn tension control device according to claim6, wherein the friction rolls of said first and second yarn engagingsurfaces are in substantial registration on opposite sides of therunning yarn, and upon pivoting movement of said rocker block, thefriction rolls of said first yarn engaging surface shift along the pathof yarn travel relative to the friction rolls of the second yarnengaging surface, thereby reducing frictional resistance applied to therunning yarn.
 8. A yarn tension control device according to claim 1,wherein said means for resiliently urging said first and second yarnengaging surfaces together comprises a compression spring.
 9. A yarntension control device according to claim 8, wherein said compressionspring is axially oriented to create a biasing force acting adjacent thesequentially spaced nip points defined by the first and second yarnengaging surfaces.
 10. A yarn tension control device according to claim9, and comprising means for selectively adjusting the biasing forcecreated by said compression spring.
 11. A yarn tension control deviceaccording to claim 10, wherein said means for selectively adjusting thebiasing force comprises a rotatable cam wheel and spring-engaging ball.12. A yarn tension control device according to claim 11, wherein saidcam wheel defines a plurality of circumferentially spaced cam surfacesof varying depth.
 13. A yarn tension control device according to claim1, and comprising a yarn cleaner located upstream of said housing.
 14. Ayarn tension control device for controlling tension in a running yarn,said tension control device comprising: a housing having a yarn guidinginlet for receiving running yarn at an unwinding tension from a yarnsupply source, and a yarn guiding outlet for guiding the running yarndownstream at a delivery tension; a pivoted rocker block carried by saidhousing, and defining a first yarn engaging surface, and wherein saidrocker block comprises a single pivot point, and said pivot point beinglocated upstream of said first yarn engaging surface; a second yarnengaging surface defined by a fixed inside wall of said housing adjacentthe first yarn engaging surface of said rocker block, and said first andsecond yarn engaging surfaces cooperating to frictionally engageopposite sides of the running yarn along a path of travel through saidhousing; said first and second yarn engaging surfaces defining arespective plurality of sequentially spaced friction rolls downstream ofsaid yarn guiding inlet; means for resiliently urging said first yarnengaging surface of said rocker block towards said second yarn engagingsurface of said housing, wherein said opposing friction rolls cooperateto form a plurality of sequentially spaced nip points adapted to adjustyarn delivery tension in response to stress variations in running yarnentering said housing, such that greater frictional resistance isapplied at said nip points to running yarn at a relatively low degree ofunwinding tension, and lesser frictional resistance is applied at saidnip points to running yarn at a relatively high degree of unwindingtension; wherein said yarn guiding inlet and said yarn guiding outletare both longitudinally offset from the sequentially spaced nip pointsalong the path of yarn travel through said housing; and a yarn cleanerlocated upstream of said housing.
 15. A yarn tension control deviceaccording to claim 14, wherein said means for resiliently urging saidfirst and second yarn engaging surfaces together comprises a compressionspring, said compression spring being axially oriented to create abiasing force acting adjacent the sequentially spaced nip points.
 16. Ayarn tension control device according to claim 15, and comprising meansfor selectively adjusting the biasing force created by said compressionspring.
 17. A yarn tension control device according to claim 16, whereinsaid means for selectively adjusting the biasing force comprises arotatable cam wheel and spring-engaging ball.
 18. A yarn tension controldevice according to claim 17, wherein said cam wheel defines a pluralityof circumferentially spaced cam surfaces of varying depth.
 19. Incombination with a textile machine, a yarn tension control device forcontrolling tension in a running yarn, said tension control devicecomprising: a housing having a yarn guiding inlet for receiving runningyarn at an unwinding tension from a yarn supply source, and a yarnguiding outlet for guiding the running yarn downstream at a deliverytension; first and second opposing yarn engaging surfaces disposedbetween said inlet and said outlet, and adapted to frictionally engageopposite sides of the running yarn along a path of travel through saidhousing; said first and second yarn engaging surfaces defining arespective plurality of sequentially spaced friction rolls downstream ofsaid yarn guiding inlet; a pivoted rocker block carried by said housing,and wherein said first yarn engaging surface is defined by an insidesurface of said rocker block, and wherein said rocker block comprises asingle pivot point, and wherein said pivot point is located upstream ofa leading one of said friction rolls; and means for resiliently urgingsaid first and second yarn engaging surfaces together, wherein saidopposing friction rolls cooperate to form a plurality of sequentiallyspaced nip points adapted to adjust yarn delivery tension in response tostress variations in running yarn entering said housing, such thatgreater frictional resistance is applied at said nip points to runningyarn at a relatively low degree of unwinding tension, and lesserfrictional resistance is applied at said nip points to running yarn at arelatively high degree of unwinding tension.
 20. A yarn tension controldevice for controlling tension in a running yarn, said tension controldevice comprising: a housing having a yarn guiding inlet for receivingrunning yarn at an unwinding tension from a yarn supply source, and ayarn guiding outlet for guiding the running yarn exiting said housing ata delivery tension; first and second opposing yarn engaging surfacesdisposed between said inlet and said outlet, and adapted to frictionallyengage opposite sides of the running yarn along a path of yarn travelthrough said housing; said first and second yarn engaging surfacesdefining a respective plurality of sequentially spaced friction rolls; acompression spring within said housing for resiliently urging said firstand second yarn engaging surfaces together, wherein said opposingfriction rolls cooperate to form a plurality of sequentially spaced nippoints adapted to adjust yarn delivery tension in response to stressvariations in running yarn entering said housing, and said compressionspring being axially oriented to create a biasing force acting adjacentthe sequentially spaced nip points, such that greater frictionalresistance is applied at said nip points to running yarn entering saidhousing at a relatively low degree of unwinding tension, and lesserfrictional resistance is applied at said nip points to running yarnentering said housing at a relatively high degree of unwinding tension;and a rotatable cam wheel and spring-engaging ball within said housingfor selectively adjusting the biasing force created by said compressionspring.
 21. A yarn tension control device according to claim 20, whereinsaid cam wheel defines a plurality of circumferentially spaced camsurfaces of varying depth.
 22. A yarn tension control device forcontrolling tension in a running yarn, said tension control devicecomprising: a housing having a yarn guiding inlet for receiving runningyarn at an unwinding tension from a yarn supply source, and a yarnguiding outlet for guiding the running yarn downstream at a deliverytension; a pivoted rocker block carried by said housing, and defining afirst yarn engaging surface; a second yarn engaging surface defined by afixed inside wall of said housing adjacent the first yarn engagingsurface of said rocker block, and said first and second yarn engagingsurfaces cooperating to frictionally engage opposite sides of therunning yarn along a path of travel through said housing; said first andsecond yarn engaging surfaces defining a respective plurality ofsequentially spaced friction rolls; a compression spring for resilientlyurging said first yarn engaging surface of said rocker block towardssaid second yarn engaging surface of said housing, wherein said opposingfriction rolls cooperate to form a plurality of sequentially spaced nippoints adapted to adjust yarn delivery tension in response to stressvariations in running yarn entering said housing, and said compressionspring being axially oriented to create a biasing force acting adjacentthe sequentially spaced nip points, such that greater frictionalresistance is applied at said nip points to running yarn at a relativelylow degree of unwinding tension, and lesser frictional resistance isapplied at said nip points to running yarn at a relatively high degreeof unwinding tension; wherein said yarn guiding inlet and said yarnguiding outlet are both longitudinally offset from the sequentiallyspaced nip points along the path of yarn travel through said housing; arotatable cam wheel and spring-engaging ball within said housing forselectively adjusting the biasing force created by said compressionspring; and a yarn cleaner located upstream of said housing.
 23. A yarntension control device according to claim 22, wherein said cam wheeldefines a plurality of circumferentially spaced cam surfaces of varyingdepth.